TPS62868: Output current

Hi team,

I received a question about the TPS62868/9 from my customer.

1. Could you tell me the difference between the TPS62868 and the TPS62869? Is that just difference in current limiting ?

2. The section of 7.3 Recommended Operating Conditions in the d/s describes the Note(2) and (3) below. Even with TPS62869, when operating continuously at 4-A output current and the junction temperature is higher than 105 °C, will the lifetime be reduced?  Also, could you tell me the reason why does the lifetime is reduced at the condition (2) and (3) below?

Note(2) TPS62868 : Lifetime is reduced when operating continuously at 4-A output current and the junction temperature is higher than 105 °C.

Note(3) TPS62869 : Lifetime is reduced when operating continuously at 6-A output current and the junction temperature is higher than 85 °C.

3. The customer is requesting information to be able to determine how much current can be flowing continuously in this device. Therefore, I would like to provide Pd(Power dissipation) at the customer's condition to the customer in order to estimate junction temp. As long as the junction temp is <105degC and output current <4A, the lifetime is not reduced. Could you calculate the Pd at the condition below? Normally, I would use Webench, but it doesn't seem to be available for this device yet.

Here is the condition. 

Vin=3.3V

Vout=0.9V

Iout=3.5A(Ave) 

Regards,

Yamaguchi